Exam 1 - Tissue Mechanics Flashcards
local shape change under the effect of applied forces
deformation
when a structure is stretched longitudinally
tension
What bears tensile loads
annular fibers
Tensile forces occur in the IVD during _______ movements
rotational
mechanical failure that occurs first in the cartilaginous endplate = ?
nuclear herniation (Schmorl’s node)
Compressive loads in extension are transmitted through the facets, leading to _______ injuries
capsular
Compressive loads applied with torque around the long axis (rotation) can produce _______ tears in the annular fibers of the IVD.
circumferential
Compression + rotation = _______ _______
annular tear
_______ is a combination of compression and tension
bending
Fractures to long bones frequently occur due to _______
bending
Loads applied parallel to the surface of the structure will cause the structure to deform internally in an angular manner
shear
_______ bones are most at risk for fractures due to shear
cancellous
In the spine, the facet joints and the fibers of the annulus fibrosus _______ shear forces
resist
The _______ provides the MAJORITY of the torsional resistance
annulus
axial rotation can strain the annulus in torsion, but ordinarily the _______ joints will protect it
zygapophyseal
spiral fractures of long bones are another example of _______ _______ _______.
torsional load failure
The external force acting to deform the material; measures the intensity of the force
stress
magnitude of deformation as a result of the applied stress/loading; a measure of the degree of deformation
strain
In general, strain is _______ to stress and the relationship is a constant for a given material and a particular type of deformation
proportional
the maximum stress a tissue can withstand without permanent deformation
strength
stress at the yield point of a material beyond which permanent deformation will occur
yield strength
the maximal stress that a material can withstand prior to the initiation of failure
ultimate strength
the stress at which the material actually breaks or ruptures
failure strength
force per unit area required to deform a material, represented by the steepness (slope) of the stress/strain curve
ductility
_______ tissues fail a low stress but can withstand a large strain
ductile (pliant)
_______ tissues can withstand high stress but fail with relatively low strain
brittle (stiff)
the total energy required to cause material failure
toughness - it takes a lot of energy to rupture a tough material
Toughness can be estimated by observing the _______ _______ under the stress/strain curve.
total area
_______ is an example material of high strength, low ductility (brittle), low toughness
bone
_______ is an example material of moderate strength and ductility, high toughness
tendon
_______ is an example material of low strength, high ductility, and moderate toughness
ligament
ability to return to the original shape when load is removed
elasticity
point at which the applied stress can lead to permanent deformation
yield point
the nonlinear response of the material after the yield point - some degree of deformation will persist after removal of the stress
plastic region
property of material to resist loads that produce shear or tensile forces
viscosity
putty-like behavior: the linear deformation produced by tensile stress remains even after the stress is removed
viscous stretch
name for when a material shows both properties of viscosity and elasticity
viscoelasticity
Viscoelastic structures will show what three time dependent loading characteristics?
Creep, hysteresis, relaxation
continued deformation over time when constantly loaded; due to expulsion of water
creep
the corresponding eventual decrease in stress that will occur as fluid is no longer exuded
relaxation
energy loss exhibited by viscoelastic materials when they are subjected to loading and unloading cycles
hysteresis
Term for normal range of motion
toe region
